Determination of the specific gravity of fluids



DETERMINATION OF THE SPECIFIC GRAVITY 0F FLUIDS March 17, 1925.

T. R. WEYMOUTH ET AL DETERMINATION OF THE SPECIFIC GRAVITY OF FLUIDS Filed Sept. 2. 1922 2 Sheets-Sheet 2 muulumluuunuaunuunm,

mvENTons Y 1Km K L Hm F Patented Mer. 17, 1925.

UNITED STATES' PATENT OFFICE.

TRUI R. WEYHOUTH, BOSS P. ANDERSON, AND JOSEPH B. FAY, 0F OIL CITY,

PENNSYLVANIA..

DATIH 0l' THE SPECIFIC GRAVITY 0l' ILUUJB.

Application lled September 2. 1822. Serial lo. 585381..

To all whom it ma concern Be it known t at we, Tnoxas R. WEY- Mou'rn, Ross P. ANnEasoN, and Josnrn R. Far, all residing at Oil City, Venango County, Pennsylvania, have invented a new and useful Improvement in the Determination of the Specific Gravity of Fluids, of which the followin is a full, clear, and exact description, re erence being had to the accompan ing` drawings, forming part of this speci cation. A

Our invention relates to apparatus for de termining the specific gravity of fluids.

In measuring fluids", either gaseous or liquid, by means of orifice meters, Pitot tubes,`

Venturi meters and other rate-reading instruments, it is necessary to know the s ecific gravity of the fluid being measured. inca the' character of fluid changes from time to time in certain cases, such as in the measurement of ses and of some liquids, it is desirable to ave a means of determining quickly and readily the specific gravity chan under such changing conditions.

It 1s well known that there are two kinds of fluid flow, namely, stream-line flow, in which the pressure drop re uired to produce the flow is practically in ependent of the density or specific gravity of the fluid, and turbulent flow, in which the pressure drop is pro ortional yto the density. The flow throug a thin plate orifice under certain conditions is turbulent, and the pressure drop accompanying the flow can therefore used as a measure of the specific gravity of the fluid. The flow through a capillary tube under proper conditions is stream-line, and the pressure dro is therefore practically independent of t e specific gravity.

In the illustrated embodiment of the invention, which is a device for determining the specific gravity of gaseous fluids, we employ a thin late orifice in which, as stated above, the difi'erential pressure is dependent upon the specific gravity of the fluid, in this case, a gas. In series with this orifice, we supply means independent of the specific gravity for measuring or regulating the amount of gta: fed to the apparatus. Such means may a capillary tu e, the rate of flow through which is independent of the specific ravity, as stated above.

B a usting the gas inlet to get a measure dilerential ressure over the capillary tube, it is possibi; to get any desired rate of flow through the apparatus. With a given flow of gas through the orifice the diferentlal ressure across the yori ce is a measure. o the pecific gravity of the gas under given con :tions of temperature and pressure.

In the accompanying drawings:

Flgurel is a diagrammatic view showm a simple form of our device comprising a t 1n plate orifice in series with a capillary tube and a manometer for each;

the capillary tube 4, .which is also provided with a U-tube manometer 5. From the ca illary tube 4 the gas is discharged into the atmosphere.

In using this simple form of apparatus, gas is admitted by opening the valve l, which is regulated to get the desired rate of flow, as indicated by the manometer 5. The reading of the manometer 3 4is then a measure of the specific gravity of the gas being tested. The scale of the manometer 3 may be calibrated to read directly in specific gravity. This reading may be corrected for temperature and barometric pressure by means of charts or tables, which may be prepared by passing gases of known specific gravity through the apparatus and varying the temperature and pressure.

In the embodiment of the invention illustrated in Figure 2, the gas enters through a diaphragm-regulated valve 6, which as hereinafter described is controlled to maintain a constant rate of iiow. After leavin the valve 6, the gas passes through a coily which is immersed in the water bath 8, maintained at a constant temperature, in order to get the gas to a constant predetermined temperature before it passes through the orifice 2.

A valve 9, controlled by a thermostat 10, regulates a gas burner 11, to maintain the tem erature of the water bath constant.

e differential pressure across the orifice 2 is a measure of the specific gravity of the s. This dierential pressure is measured and recorded by means of a U-tube manometer 12, filled with mercur and having a Boat 13, which is connect with a st lus 14,y for recording the rassure on a chart 15, which may be riven by clockwork. This oat type recording gauge is well known in this art, and nee not be illustrated or described in greater detail.

The gas flows from the orifice 2 through a capillary tube 4, also immersed in the constant temperature water bath 8.

'lhe diti'erential pressure across the capillary tube 4 is indicated by means of a U-tube manometer 16, which is provided with an inclined portion 17, like an ordinary draft gau in order to give accurate readings.

'flle valve 6 is automatically regulated to maintain a constant flow of the glas across the orifice by means of the diap rag'm 18 connected to the valve stem 19. A tube 20 at the inlet end of the capillary tube 4' transmits pressure at this point to the upper side of the -diaphragm 18. and a tube 21 connected at the outer end of the capillary tube 4 transmits pressure at this point to the underside of the diaphragm 18. Since the diierential pressure across the capillary tube 4 is independent of the specific gravity and at a constant pressure and tempera-ture is de endent upon the rate of dow, the valve 6 wi l maintain a constant rate of flow thro h the apparatus independently of the speci c gravity of tbe as. A thumbscrew 22oper ating on the va ve spring 23 is used to adjust the rate of flow to any desired predetermined amount to keep any desired constant differential pressure across the capillary tube 4, as indicated by the manometer 16.

The gas flows from the capillary tube 4 through a diaphragm-operated valve 24, to the dischar e tube 25. Above the valvecontrolling iaphragm 26 is a closed chamber 27, so as to maintain a constant pressure above the diaphragm. This pressure may be varied by admltting or letting out air through the valve 28. The entire valve body, including the chamber 27, is immersed in the constant temperature water bath 8.

A thumbscrew 29 operating on the valve spring 30 provides an adjustment by means of which the exit pressure of the gas from the capillary tube may be adjusted. The valve is preferabl adjusted so that this exit pressure is sli ht y above atmospheric pressure. The va ve serves to maintain such exit preure regardless of the barometric fluctuations.

Since the valve 6 maintains a constant di'erental pressure across the capillary tube and since the valve 24 maintains a constant absolute pressure at the exit of the capillary tube, the rate of ow of gas through the apparatus will be maintained constant. Any variations in the diferential pressurexacross the orifice 2 will be a true mesaure of the variation in the specific gravity of the gas bein measured, since the temeratureis maintalned constant by the water bath and the pressure is maintained constant by the valves 6 and 24. The specific gravity is recorded on the chart 15 which may be graduated to read the specific gravity diile the drawings illustrate the preferrcd embodiments o our invention, it will be understood that various changes may be made in thc details of construction or mode of operation withinthe scope of the following claims.

We claim:

1. Apparatus for measuring the specific gravity of fluids, comprising a casing having twochambers with a connecting orifice, means for supplying Huid to said orifice at a determinate rate, and means for measuring the differential pressure between the two chambers, substantially as described.

2. Apparatus for measuring the specific gravity of iiuids, comprisin a pipe with an obstruction having an ori ce, means for measuring the pressure on opposite sides of the obstruction, and means inde dent of the specific gravity of the fluid or regulating the rate of iow through the orifice, substantially as described.

3. Apparatus for measuring the specic gravity of fluids, comprising a pipe provided with an obstruction having an orifice, means for measuring the differential ressure developed by the iuid flow throng the orifice, a capillary tube in series with the orificez and means for measuring the differential pressure developed b said fluid flow through the capillary tu e, substantially as described.

4. Apparatus for measuring the specific vity of fluids, comprising a :dow pipe aving an obstruction with an orifice, means for measurin the dierential rassure acmss thc ori ce, a capillary tube 1n series with the orifice, and means for maintaining a constant pressure dili'erence between the ends of said capillary tube, substantially as described. n

5. Apparatus for measuring the specific lgravity of fluids, comprising a ow pipe aving an obstruction with an orifice, means for measurin the diierential ressure across the ori ce, a capillary tube in series with the orifice, means for maintaining a constant pressure difference between the ends of the capillary tube, and means for maintaining a constant outlet pressure on the capillary tube, substantially as described.

6. pparatus for measuring the specific vity of fluids, comprising a ow pipe ving an obstruction with an orice, means for measuring the differential preure across the orifice, means independent of the s ecic gravity for measuring the rate of ow through the orifice, and means for maintaining the fluid flowing through the apparatus at a constant temperature, substantially as described.

7. Apparatus for measuring the specic gravity of fluids, comprising a flow pipe aving an obstruction with an orifice, means for measurin the differential pressure across the ori ce, a capillary tube in series with the orifice, and means for maintaining the fluid flowing through the orifice and capillary tube at a constant temperature, substantiall as described.

8. Apparatus or measuring the specific avity of fluids, comprising a fiow pipe aving an obstruction with an orifice, means for recordin the differential pressure across the ori ce, and means for maintaining a determinate flow of the fluid through the orifice, substantially as described.

9. Apparatus for measuring the specific gravity of fiuids, .comprising a flow pipe aving an obstruction with an orifice, means for recording the differential pressure across the orifice, a capillary tube 1n series with the orice, means for maintaining a constant pressure difference between the ends of the capillary tube, means for maintaining a constant outlet ressure on the capillary' tube, and means or maintaining the fiuid flowing through the orifice and capillary tube at a constant temperature, substantially as described.

10. Apparatus for measuring the specific gravity of fluids, comprising means dependent only on the specific gravity and the flow of fluid through the apparatus for recordin the specific gravity, and means for maintaining a determinate rate of fiow through said means, substantially as dcscribed.

1l. Apparatus for measuring the specific gravity of fluids, comprising measurin means dependent on the specific gravity an the rate of flow of the fluid, a ca illary tube in series with said means, an automatic variable means for maintaining a constant pressure difference between the ends of the capillary tube, substantially as described.

In testimony whereof we have hereunto Set our hands.

THOMAS R. WEYMOUTH. ROSS P. ANDERSON. JOSEPH R. FAY.

across the orifice, means independent of the s ecific gravity for measuring the rate of ow through the orifice, and means for maintaining the fiuid flowing through the apparatus at a constant temperature, substantially as described.

7. Apparatus for measuring the specific gravity of fiuids, comprising a flow pipe aving an obstruction with an orifice, means for measurin the differential pressure across the ori ce, a capillary tube in series with the orifice, and means for maintaining the fiuid fiowing through the orifice and capillary tube at a constant temperature, substantiall as described.

8. Apparatus for measuring the specific gravity of fluids, comprising a How pipe aving an obstruction with an orifice, means for recordin the differential pressure across the ori ce, and means for maintaining a determinate flow of the fiuid through the orifice, substantially as described.

9. Apparatus for measuring the specific avity of fiuids, comprising a fiow pipe aving an obstruction with an orifice, means for recording the differential pressure across the orifice, a capillary tube 1n series with the orifice, means for maintaining a constant pressure difference between the ends of the capillary tube, means for maintaining a constant outlet ressure on the capillary tube2 and means fiir maintainin the fluid fiowing through the orifice an capillary tube at a constant temperature, substantially as described.

10. Ap aratus for measuring the specific gravit o fluids, comprising means dependent on y on the specific gravity and the flow of fluid through the apparatus for recordin the specific gravity, and means for maintaining a determinate rate of flow through said means, substantially as dcscribed.

11. Apparatus for measuring the specific gravity of fiuids, comprising measuring means dependent on the specific gravity an the rate of flow of the fiuid, a capillary tube in series with said means, and automatic variable means for maintaining a constant pressure difference between the ends of the capillary tube, substantially as described.

In testimony whereof we have hereunto set our hands.

THOMAS R. WEYMOUTH. ROSS P. ANDERSON. JOSEPH R. FAY.

Certificate of Correction.

It is hereby certified thatin Letters Patent No. 1,530,222, granted Marc-h 17 1925, uplon the ap lication of Thomas R. Weymouth, RossA P. Anderson, and

Joseph Fay, of

il City, Pennsylvania, for an improvement in Determination of the Specific Gravity of Fluids, an error appears in the printed specification requiring correction as follows: Page 3, line 42, claim 10, for the word n ieans read apparatus; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent ce. Signed and sealed this 28th day of April, A. D. 1925.

[man] KARL FENNING, Acting Commissioner of Patents.

-Certicate of Correction.

It is hereby ertifed that in Letters Patent No. 1,530,222, granted March 17, 1925, uron the apglication of Thomas R. Weymouth, Ross P. Anderson, and Joseph Fey, of il City, Pennsylvania, for an improvement in Determination of the. Specific Gravity of Fluids, an error appears in the printed specification requiring correction as follows: Page 3, line 42, claim 10, for the word means IBaq apparatus; and that the said Letters Patent should be read with this co1'- Itlon therein that the Same may conform to the record of the case in the Patent Slgned and sealed this 28th day of April, A. D. 1925.

[wn] f KARL FENNING,

Acting Commissioner of Patems. 

